1.2.1 system software Flashcards
what is an operating system?
a collection of programs that work together to provide an interface between the user and the computer
give 3 functions of an operating system
memory management, resource management and user interface
what are the similarities and differences between paging and segmentation?
both: are used when ram space is insufficient, can cause disk thrashing
paging: uses equal sized sections called pages
segmentation: use variable sized, logical sections called segments
describe how virtual memory is used when there is not enough ram.
a section of the hard drive used used to act as RAM, sections of programs not currently being used are temporarily moved into virtual memory through paging, this frees up memory for other programs in RAM
What is an interrupt?
a single generated by software or hardware to indicate to the processor that a process needs attention
are these scheduling algorithms pre-emptive or non pre-emptive? FCFS, SRT, SJF,MLFQ,RR
pre-emptive: RR, SRT, MLFQ
non pre-emptive: FCFS, SJF
what are the advantages and disadvantages of using multilevel feedback queues for scheduling ?
ad - services most urgent interrupts first
dis - hard to implement
define a real time operating system and when it may be used.
real time operating system performs a task within a guaranteed Time frame, they are are in systems were a response within a given time frame is critical eg life support systems, self driving cars and power systems
describe 3 functions of the BIOS
power on self test (POST), checking the CPU clock memory and processor, testing for external memory devices
what is the role of a device driver?
enable the operating system to interact with hardware devices
describe an instance in which a virtual machine may be used
testing programs, protection from malware, running software compatible with different versions and types of operating systems
